1. Field of the Invention
The present invention relates in general to image noise reduction, and more specifically to a gain controlled threshold in a denoising filter for image signal processing.
2. Description of the Related Art
Noise reduction is a key component in any imaging system. Noise filtering may be applied at various steps of an image signal processing (ISP) chain. In post-processing, at the output of the ISP chain, denoising reduces any residual noise prior to encoding. Noise in the image is caused by many factors including noise generated by the sensor and in the ISP chain. In conventional configurations, external manual control by the user was used to adjust parameters in the processing chain including those associated with denoising filters. When a conventional image processing system was used within a handheld camera, for example, the user made external adjustments in an attempt to improve the quality of the image displayed on the camera monitor. Such subjective manual adjustment was inconvenient, time-consuming, and error prone often resulting in less than optimal image quality.